Eupatorieae

Eupatorieae is a large tribe of flowering plants in the family Asteraceae, within the subfamily Asteroideae. The tribe includes about 60 genera and more than 1,000 species, with the majority native to the Americas, especially tropical and subtropical regions; a few species have become naturalized elsewhere.

Taxonomy and characteristics: Historically many species were placed in Eupatorium, but modern classifications divide the group into numerous genera such as Ageratina, Chromolaena, Conoclinium, Praxelis, and Stevia. Members are typically herbaceous perennials or shrubs. Leaves are usually opposite and may be aromatic. The inflorescences are heads (capitula) composed almost exclusively of disc florets, with ray florets typically absent. The fruit is a dry cypsela; a pappus, if present, is often reduced or absent, affecting dispersal.

Distribution and ecology: Eupatorieae plants occur predominantly in the Americas, from temperate to tropical habitats, often in disturbed or edge environments. They are mainly pollinated by insects, especially bees and butterflies. Some species have become invasive in tropical regions, such as Chromolaena odorata, commonly known as Siam weed. Others are cultivated as ornamentals, and a few have traditional medicinal uses. Ongoing molecular studies continue to revise genus boundaries within the tribe.